Automatic position determination of head mounted display optics

ABSTRACT

A head mounted display (HMD) includes an electronic display, an optical element, and a light sensor. The electronic display is configured to generate a pixel pattern of display light and the optical element is disposed to pass the display light to a user of the HMD. The light sensor is disposed proximate to the optical element to generate light measurements in response to the pixel pattern. The light measurements are representative of a lateral position of the optical element with respect to the electronic display.

CROSS-REFERENCE TO RELATED APPLICATION

This application is related to a U.S. non-provisional patent applicationentitled, “AUTOMATIC IMAGE ALIGNMENT WITH HEAD MOUNTED DISPLAY OPTICS,”filed Aug. 5, 2019.

FIELD OF DISCLOSURE

Aspects of the present disclosure relate generally to head mounteddisplays (HMDs), and in particular but not exclusively, relate to HMDsthat include movable optics.

BACKGROUND

A head mounted display (HMD) is a display device, typically worn on thehead of a user. HMDs may be used in a variety of applications, such asgaming, aviation, engineering, medicine, entertainment and so on toprovide artificial reality content to a user. Artificial reality is aform of reality that has been adjusted in some manner beforepresentation to the user, which may include, e.g., virtual reality (VR),augmented reality (AR), mixed reality (MR), hybrid reality, or somecombination and/or derivative thereof. Some HMDs may be configured toallow binocular viewing by the user (e.g., allow viewing by both eyes).

Because the HMD may be used by different people, the distance betweenthe left and right eye pieces may be made adjustable to account forvariations in interpupillary distance (IPD). In some contexts, IPDrefers to the distance between the centers of the pupils of a person'seyes. In the context of HMDs, the term “IPD” may be used to describe thedistance between the exit pupils or optical axes of the optics of abinocular HMD. For some uses, incorrect adjustment of the IPD of the HMDmay lead to an uncomfortable viewing experience and/or eye strain. Inaddition, adjustment of the IPD may change the position of the opticsrelative to an electronic display included in the HMD. However, changingthe position of the optics relative to the electronic display maynegatively affect the viewing of images rendered by the HMD, especially3D or stereoscopic images. Thus, changes in the position of the opticsmay lead to a reduction in the immersion or presence experienced by theuser.

BRIEF DESCRIPTION OF THE DRAWINGS

Non-limiting and non-exhaustive aspects of the present disclosure aredescribed with reference to the following figures, wherein likereference numerals refer to like parts throughout the various viewsunless otherwise specified.

FIG. 1 illustrates an example head mounted display (HMD), in accordancewith aspects of the present disclosure.

FIG. 2 illustrates an optical system of an HMD that includes adjustableeyecup housings, in accordance with aspects of the present disclosure.

FIG. 3 illustrates a side view of an electronic display and anadjustable eyecup housing of an HMD, in accordance with aspects of thepresent disclosure.

FIG. 4 illustrates a plan view of an electronic display and indicationsof the positions of a light sensor and a center of an optical element,in accordance with aspects of the present disclosure.

FIG. 5 illustrates pixel pattern of display light generated by anelectronic display and corresponding light measurements of a lightsensor, in accordance with aspects of the present disclosure.

FIGS. 6A-6D illustrate various pixel patterns of display light generatedby an electronic display, in accordance with aspects of the presentdisclosure.

FIG. 7 illustrates an example position determination controller, inaccordance with aspects of the present disclosure.

FIG. 8A is a flow chart illustrating an example process of automaticposition determination of HMD optics, in accordance with aspects of thepresent disclosure.

FIG. 8B is a flow chart illustrating an example process of determining alateral position of an optical element, in accordance with aspects ofthe present disclosure.

FIG. 9 is a flow chart illustrating an example process of automaticimage alignment with HMD optics, in accordance with aspects of thepresent disclosure.

FIGS. 10A and 10B illustrate the rendering of an example image by anelectronic display of an HMD that includes the adjustment of a renderingcenter of the electronic display, in accordance with aspects of thepresent disclosure.

DETAILED DESCRIPTION

Various aspects and embodiments are disclosed in the followingdescription and related drawings to show specific examples relating tothe automatic position determination of head mounted display (HMD)optics. Alternate aspects and embodiments will be apparent to thoseskilled in the pertinent art upon reading this disclosure and may beconstructed and practiced without departing from the scope or spirit ofthe disclosure. Additionally, well-known elements will not be describedin detail or may be omitted so as to not obscure the relevant details ofthe aspects and embodiments disclosed herein.

As mentioned above, an HMD may include movable optics that allows usersto adjust for various interpupillary distances (IPDs). However, changingthe position of the optics may change their position relative to theelectronic display of the HMD, which may degrade the user's viewingexperience as some images, such as 3D images, may not appear asintended. Accordingly, aspects of the present disclosure provide for oneor more mechanisms that provide for the automatic determination of theposition of one or more optical elements (e.g., lenses) of an HMD. Insome examples, the electronic display of the HMD is configured (ortriggered) to generate a pixel pattern of display light. The position ofthe pixel pattern generated on the electronic display may be varied(e.g., swept across the electronic display). A light sensor includednext to or near the optical element may generate light measurements asthe pixel pattern is displayed. The light measurements may then beanalyzed to determine a current position of the optical element based,in part, on a known and/or calibrated distance between the light sensorand the optical element, itself.

In addition, aspects of the present disclosure provide for the automaticalignment of images generated by the HMD with the optical elements. Thatis, once a current position of the optical element is determined, arendering center of the electronic display may be adjusted to alignsubsequent images with the current position of the optical element.These and other features will be described in more detail below.

FIG. 1 illustrates an HMD 100, in accordance with aspects of the presentdisclosure. The illustrated example of HMD 100 is shown as including aviewing structure 140, a top securing structure 141, a side securingstructure 142, a rear securing structure 143, and a front rigid body144. In some examples, the HMD 100 is configured to be worn on a head ofa user of the HMD 100, where the top securing structure 141, sidesecuring structure 142, and/or rear securing structure 143 may include afabric strap including elastic as well as one or more rigid structures(e.g., plastic) for securing the HMD 100 to the head of the user. HMD100 may also optionally include one or more earpieces (not shown) fordelivering audio to the ear(s) of the user of the HMD 100.

The illustrated example of HMD 100 also includes an interface membrane118 for contacting a face of the user of the HMD 100, where theinterface membrane 118 functions to block out at least some ambientlight from reaching to the eyes of the user of the HMD 100.

Example HMD 100 may also include a chassis for supporting hardware ofthe viewing structure 140 of HMD 100 (chassis and hardware notexplicitly illustrated in FIG. 1). The hardware of viewing structure 140may include any of processing logic, wired and/or wireless datainterface for sending and receiving data, graphic processors, and one ormore memories for storing data and computer-executable instructions. Inone example, viewing structure 140 may be configured to receive wiredpower and/or may be configured to be powered by one or more batteries.In addition, viewing structure 140 may be configured to receive wiredand/or wireless data including video data.

In some examples, an interpupillary distance (IPD) adjustment mechanism150 may be included in the viewing structure 140 to allow foradjustments to the IPD of the HMD 100. As shown in FIG. 1, the IPDadjustment mechanism 150 may include a button 152 (or other mechanicalfeature) that is movable by the user of the HMD 100. Movement of thebutton 152 causes lateral movement of one or more adjustable eyecuphousings included in the viewing structure 140. In some examples, theamount of adjustment to the IPD of the HMD 100 is determined by how muchthe user moves the button 152.

By way of example, FIG. 2 illustrates a face of an optical system 200(e.g., facing the electronic display) of an HMD that includes adjustableeyecup housings 202A and 202B. Optical system 200 is shown as includinga first (e.g., right-eye) adjustable eyecup housing 202A, a second(e.g., left-eye) adjustable eyecup housing 202B, a first (e.g.,right-eye) optical element 206A, a second (e.g., left-eye) opticalelement 206B, a first light sensor 208A, a second light sensor 208B, anda gear assembly 210. Also shown in FIG. 2 are an exit pupil 212A and anexit pupil 212B. Optical system 200 is one possible implementation of anoptical system that may be incorporated into an HMD, such as HMD 100 ofFIG. 1. For example, in one aspect, optical system 200 may be integratedinto viewing structure 140 of HMD 100 for passing display light (e.g.,light generated by an electronic display) to the eyes of a user.

As shown in FIG. 2, gear assembly 210 is coupled to the first and secondadjustable eyecup housings 202A/202B. In one example, gear assembly 210is mechanically coupled to button 152 of FIG. 1 to allow a user toadjust a lateral position of the optical elements 206A and 206B. Thatis, movement of the button 152 may cause lateral movement (e.g., lateralmovements 204A and 204B along the x-axis) of the first and secondadjustable eyecup housings 202A/202B via rotation of gear assembly 210.In some embodiments, the lateral movements 204A and 204B are symmetric,but in opposite directions. That is, gear assembly 210 may cause thesimultaneous movement of both the adjustable eyecup housings towards oneanother (i.e., towards a nasal bridge or a center region of the HMD). Inother example, gear assembly 210 may cause the simultaneous movement ofboth the adjustable eyecup housings away from one another (i.e., towardsrespective temple regions of the HMD). In some aspects, rotation of thegear assembly 210 causes lateral movement of one or more of theadjustable eyecup housings 202A/202B resulting in an adjustment of theIPD of the HMD.

The first adjustable eyecup housing 202A and the second adjustableeyecup housing 202B may include a respective optical element 206A/206B.The optical elements 206A and 206B may include one or more of a lens, amirror, a diffuser, a filter, a polarizer, a prism, a window, a beamsplitter, a diffractive element, or the like. The optical elements 206Aand 206B are configured to receive display light generated by one ormore electronic displays of the HMD and to direct/pass at least some ofthe display light to a user. In some examples, optical elements 206A and206B are fixedly mounted to their respective adjustable eyecup housing,such that lateral movements of the adjustable eyecup housing results inthe same lateral movement of the optical element. In one aspect, lateralmovement 204A of the first optical element 206A relative to lateralmovement 204B of the second optical element 206B changes a distancebetween their exit pupils 212A and 212B, and accordingly changes the IPDof the HMD. For example, a user may move the button 152 of FIG. 1 in onedirection to increase the IPD of the HMD and may move the button 152 inthe opposite direction to decrease the IPD.

In some aspects, the exit pupils 212A and 212B represent a center oftheir respective optical elements 206A/206B. Even still, in someexamples, exit pupils 212A and 212B may be virtual apertures of theirrespective optical elements where only display light passing throughthis virtual aperture enters into the eye of the user. In some examples,the IPD of the HMD is the distance between exit pupil 212A and exitpupil 212B.

As further shown in FIG. 2, each adjustable eyecup housing may include alight sensor. For example, the first adjustable eyecup housing 202A isshown as including the first light sensor 208A and the second adjustableeyecup housing 202B is shown as including the second light sensor 208B.Light sensors 208A and 208B may include any active or passive sensor formeasuring an aspect of the display light, such as its intensity. Forexample, light sensors 208A and 208B may include one or more of aphotodiode, a phototransistor, or a photoresistor. In some aspects, thelight sensors 208A and 208B are fixedly attached to their respectiveadjustable eyecup housings such that movement of the adjustable eyecuphousings results in the same movement of the light sensor. In someexamples, light sensors 208A/208B are disposed proximate to theirrespective optical elements facing the electronic display to generatelight measurements in response to display light that is generated by theelectronic display. In some embodiments, the light sensors 208A/208B aredisposed a known or calibrated distance from the center of theirrespective optical element. For example, light sensor 208A is shown asdisposed a calibrated distance 205A from the exit pupil 212A of opticalelement 206A. Similarly, light sensor 208B is disposed a calibrateddistance 205B from the exit pupil 212B of the optical element 206B.

In operation, the light sensors 208A and 208B are configured to generatelight measurements (e.g., intensity values) of display light generatedby the electronic display. For example, FIG. 3 illustrates a side viewof an electronic display 304 and an adjustable eyecup housing 302 of anoptical system 300, in accordance with aspects of the presentdisclosure. Optical system 300 is shown as including an electronicdisplay 304 and an adjustable eyecup housing 302. Adjustable eyecuphousing 302 is shown as including an optical element 306 and a lightsensor 308. Optical system 300 is one possible example of optical system200 of FIG. 2.

The electronic display 304 is configured to display or render images(e.g., 2D or 3D images) for presentation to the user. In variousembodiments, the electronic display 304 comprises a single electronicdisplay panel or multiple electronic display panels (e.g., a display foreach eye of a user). Electronic display 304 may include a liquid crystaldisplay (LCD), an organic light emitting diode (OLED) display, aninorganic light emitting diode (ILED) display, a micro light emittingdiode (mLED), an active-matrix organic light-emitting diode (AMOLED)display, a transparent organic light emitting diode (TOLED) display,some other display, or any combination thereof. In some implementations,adjustable eyecup housing 302 is configured to allow movement of theoptical element 306 that is independent of the electronic display 304.That is, changes in the lateral position of the adjustable eyecuphousing 302 (and thus the optical element 306) may change the positionof the optical element 306 with respect to the electronic display 304.

In operation, the electronic display 304 is configured to generatedisplay light for presentation to the user. For example, as shown inFIG. 3, electronic display 304 generates display light 310, which ispassed (e.g., focused) by the optical element 306 from the display side303 to the eyeward side 305 and then to the exit pupil 312 to an eye ofa user.

FIG. 3 also shows the light sensor 308 disposed on the display side 303of the adjustable eyecup housing 302. The light sensor 308 is disposedproximate to the optical element 306 such that at least some of thedisplay light 310 generated by the electronic display 304 is incident onthe light sensor 308. As mentioned above, the light sensor 308 may bedisposed a known or calibrated distance from the exit pupil 312.Although FIG. 3 illustrates light sensor 308 at a particular position onthe display side 303 of the adjustable eyecup housing 302, light sensor308 may be positioned at any location on the display side 303 providedthat the distance between the light sensor 308 and the exit pupil 312 isknown and/or calibrated. Thus, in some examples, the electronic display304 may be configured to generate a pixel pattern of display light 310in order to determine a lateral position of the optical element 306. Forexample, the location of the pixel pattern generated on the electronicdisplay 304 may be varied (e.g., swept across the electronic display304), where the light sensor 308 then generates a plurality of lightmeasurements as the pixel pattern is displayed. The light measurementsmay then be analyzed to determine a current position of the opticalelement 306 based, in part, on the known or calibrated distance betweenthe light sensor 308 and the exit pupil 312.

For example, FIG. 4 illustrates a plan view of an electronic display402. Electronic display 402 is one possible implementation of any of theelectronic displays discussed herein, including the electronic displayincluded in the HMD 100 of FIG. 1 and/or the electronic display 304 ofFIG. 3. The illustrated example of electronic display 402 is shown as atwo-dimensional (“2D”) array of pixels (e.g., pixels P1, P2 . . . , Pn).In one embodiment, each pixel is light emitting device, such as alight-emitting diode (LED). As illustrated, each pixel is arranged intoa row (e.g., rows R1 to Ry) and a column (e.g., column C1 to Cx) topresent an image of a person, place, or object to a user of the HMD.

In addition to rendering images for presentation to the user, theelectronic display 402 may also be configured to generate one or morepixel patterns of display light for determining a lateral position ofthe optical element of the HMD. For example, FIG. 4 illustrates thecurrent lateral position 404 of the light sensor with respect to theelectronic display 402. While the pixel pattern of display light isgenerated by the electronic display 402, the light sensor may generatelight measurements, such as intensity values. Based on the lightmeasurements, the HMD may determine a first display coordinate of theelectronic display 402 that is aligned with the light sensor. Withreference to the example illustrated in FIG. 4, the HMD may analyze thelight measurements to determine that the display coordinate aligned withthe light sensor is the column associated with pixel Pi.

FIG. 4 also illustrates the current lateral position 406 of the opticalelement of the HMD. In some examples, the lateral position 406 of theoptical element represents the center or exit pupil of the opticalelement. Once the current lateral position 404 of the light sensor isdetermined, the HMD may then determine the display coordinate that isaligned with the current lateral position 406 of the optical element. Insome examples, the display coordinate of the optical element isdetermined based on a known or calibrated distance between the lightsensor and the center of the optical element. In the illustrated exampleof FIG. 4, the display coordinate aligned with the center of the opticalelement is the column associated with pixel Pj. Thus, in some aspects,the current lateral position 406 of the optical element is a position ofthe exit pupil of the optical element with respect to at least one pixel(e.g., pixel Pj) of the electronic display 402.

As mentioned above, the light sensor may be configured to generate lightmeasurements based on a pixel pattern of display light that is generatedby the electronic display 402. In some examples, a location of the pixelpattern on the electronic display is varied, where the light sensorgenerates a light measurement corresponding to each location of thepixel pattern that is displayed. The electronic display 402 may beconfigured to render a variety of pixel patterns and to vary thelocation of the pixel pattern in a variety of ways. For example, FIG. 5illustrates a pixel pattern 504 that includes a single column of pixels.FIG. 5 also illustrates a current lateral position 502 of the lightsensor. Thus, in some embodiments, the light sensor is configured togenerate a light measurement (e.g., intensity value) for each of aplurality of locations that the pixel pattern 504 is rendered on theelectronic display 402. For example, the light sensor may generate afirst light measurement when the pixel pattern 504 is illuminated atcolumn C1, a second light measurement when the pixel pattern 504 isilluminated at column C2, and so on. In some examples, the pixel patternis sequentially swept across the electronic display 402 (e.g., columnC1, then column C2, then column C3, etc.). In other examples, thelocation of the pixel pattern displayed may be non-sequential (e.g.,column C4, then column C1, then column Cx, etc.).

FIG. 5 also illustrates a plurality of light measurements 506 that aregenerated by the light sensor as the location of the pixel pattern 504is varied on the electronic display 402. As shown in FIG. 5, the lightmeasurements 506 may include intensity values of the display lightmeasured by the light sensor. The light measurements 506 may then beanalyzed to determine a current position of the light sensor. In someembodiments, analyzing the light measurements 506 includes determining apeak intensity value 508. In the example of FIG. 5, the peak intensityvalue 508 corresponds to a location coordinate associated with thecolumn of pixel Pi. Thus, the HMD may determine that the current lateralposition 502 of the light sensor is aligned with the column associatedwith pixel Pi.

FIGS. 6A-6D illustrate various alternative pixel patterns of displaylight generated by electronic display 402, in accordance with aspects ofthe present disclosure. For example, FIG. 6A illustrates a pixel pattern602 that includes a single column of pixels segmented into severalgroups 604A-604E of pixels. As with the single column pixel pattern 504of FIG. 5, the location of pixel pattern 602 may be varied on electronicdisplay 402 to generate a plurality of light measurements. Thus, in someembodiments, each light measurement generated by the light sensor mayinclude an intensity value measured while a single column of segmentedpixels is illuminated by the electronic display 402.

FIG. 6B illustrates another example pixel pattern 606 that includesmultiple columns of pixels. As with the single column pixel pattern 504of FIG. 5, the location of pixel pattern 606 may be varied on electronicdisplay 402 to generate a plurality of light measurements. Thus, in someembodiments, each light measurement generated by the light sensor mayinclude an intensity value measured while multiple columns of pixels aresimultaneously illuminated by the electronic display 402. Although FIG.6B illustrates the pixel pattern 606 as including three columns ofpixels, pixel pattern 606 may include any number of simultaneouslyilluminated columns including two or more.

FIG. 6C illustrates yet another example pixel pattern 608 that includesmultiple columns segmented into several groups of pixels 610A-610E. Aswith the single column pixel pattern 504 of FIG. 5, the location ofpixel pattern 608 may be varied on electronic display 402 to generate aplurality of light measurements. Thus, in some embodiments, each lightmeasurement generated by the light sensor may include an intensity valuemeasured while multiple columns of segmented pixels are simultaneouslyilluminated by the electronic display 402. Although FIG. 6C illustratesthe pixel pattern 608 as including three columns of segmented pixels,pixel pattern 608 may include any number of simultaneously illuminatedcolumns including two or more.

FIG. 6D illustrates an example pixel pattern 610 that includes a singlepixel. As with the single column pixel pattern 504 of FIG. 5, thelocation of pixel pattern 610 may be varied on electronic display 402 togenerate a plurality of light measurements. Thus, in some embodiments,each light measurement generated by the light sensor may include anintensity value measured while a single pixel is illuminated by theelectronic display 402. In some aspects, the example pixel patterns 504,602, 606, and 608 of FIGS. 5-6C may result in light measurements havinga higher dynamic range as compared to the single pixel pattern 610 ofFIG. 6D. Having a higher dynamic range may increase the accuracy whenanalyzing the light measurements, such as when determining a peakintensity value. However, in some examples, varying the location of thesingle pixel pattern 610 may include varying both the column and row ofthe single pixel that is illuminated. Thus, using a single pixel, suchas the pixel pattern 610 of FIG. 6D may allow for the determination ofnot only the lateral position of the light sensor along the x-axis butalso for determining the vertical position of the light sensor along they-axis.

FIG. 7 illustrates an example position determination controller 702, inaccordance with aspects of the present disclosure. The illustratedexample of position determination controller 702 is shown as including acommunication interface 704, one or more processors 706, hardware 708,and a memory 710. The position determination controller 702 is onepossible implementation of a computing device that may be incorporatedinto, or communicatively coupled to, the HMD 100 of FIG. 1.

The communication interface 704 may include wireless and/or wiredcommunication components that enable the position determinationcontroller 702 to transmit data to and receive data from other devices.The hardware 708 may include additional hardware interface, datacommunication, or data storage hardware. For example, the hardwareinterfaces may include a data output device (e.g., electronic display,audio speakers), and one or more data input devices.

The memory 710 may be implemented using non-transitory computer-readablemedia, such as computer storage media. In some aspects,computer-readable media may include volatile and/or non-volatile,removable and/or non-removable media implemented in any method ortechnology for storage of information such as computer-readableinstructions, data structures, program modules, or other data.Computer-readable media includes, but is not limited to, RAM, ROM,EEPROM, flash memory or other memory technology, CD-ROM, digitalversatile disks (DVD), high-definition multimedia/data storage disks, orother optical storage, magnetic cassettes, magnetic tape, magnetic diskstorage or other magnetic storage devices, or any other non-transmissionmedium that can be used to store information for access by a computingdevice.

The processors 706 and the memory 710 of the position determinationcontroller 702 may implement a pattern generator module 712, a lightsensor module 714, and a display adjustment module 716. The patterngenerator module 712, light sensor module 714, and display adjustmentmodule 716 may include routines, program instructions, objects, and/ordata structures that perform particular tasks or implement particularabstract data types. The memory 710 may also include a data store (notshown) that is used by the pattern generator module 712, light sensormodule 714, and display adjustment module 716.

The pattern generator module 712 may be configured to generate one ormore control signals 718 to trigger or direct the electronic display(e.g., electronic display 304 of FIG. 3) to generate a pixel pattern ofdisplay light. In some examples, the pattern generator module 712generates the control signals 718 as part of a startup procedure (e.g.,upon powering on) of the HMD. In other examples, the pattern generatormodule 712 may generate the control signals 718 in response to inputreceived from the user, either by way of a software calibration featureand/or in response to detecting that the user has adjusted the IPD(e.g., by detecting movements of the button 152 of FIG. 1). In someexamples, the pattern generator module 712 may generate the controlsignals 718 to direct the electronic display to present any of the pixelpatterns discussed herein, such as pixel pattern 504 of FIG. 5, pixelpattern 602 of FIG. 6A, pixel pattern 606 of FIG. 6B, pixel pattern 608of FIG. 6C, and/or pixel pattern 610 of FIG. 6D. In addition, thepattern generator module 712 may generate the control signals 718 tovary the location of the pixel pattern that is presented on theelectronic display.

The light sensor module 714 may be configured to receive/obtain aplurality of light measurements 720 generated by the light sensor inresponse to the illumination of the pixel pattern on the electronicdisplay. In some examples, the light sensor module 714 is configured toassociate each of the received light measurements with a correspondingdisplay coordinate. That is, a first light measurement may be associatedwith a first column of the electronic display when the pixel pattern isilluminated at or about the first column. Similarly, a second lightmeasurement may be associated with a second column of the electronicdisplay when the pixel pattern is illuminated at or about the secondcolumn.

In some aspects, the light sensor module 714 may be configured toanalyze the light measurements 720 to determine the lateral position ofthe light sensor and/or the lateral position of the optical element. Asdiscussed above, in one example, analyzing the light measurements 720may include determining a peak intensity value of the light measurements720 (e.g., peak intensity value 508 of FIG. 5). As shown in FIG. 7, thelight sensor module 714 may be configured to generate an output 719. Insome examples, output 719 is representative of the current lateralposition of the light sensor and/or optical element. In some examples,the output 719 may also be representative of a current IPD of the HMD.That is, in some examples, the light sensor module 714 may determine alateral position of a first optical element (e.g., left-eye opticalelement) and a lateral position of a second optical element (e.g.,right-eye optical element). The light sensor module 714 may thendetermine the IPD based on a distance between the determined lateralpositions of the two optical elements.

As shown in FIG. 7, the memory 710 may also include a display adjustmentmodule 716. As will be described in more detail below with reference toFIGS. 9, 10A and 10B, the display adjustment module 716 may beconfigured to adjust a rendering center of the electronic display. Thatis, the display adjustment module 716 may be configured to generate anoffset 722 to move/adjust the rendering center of the electronic displaybased on the output 719 (e.g., lateral positions, IPD, etc.) generatedby the light sensor module 714. In some examples, adjusting therendering center of the electronic display may adjust where images arepresented on the electronic display with respect to the optical elementsof the HMD. Even still, adjusting the rendering center of the electronicdisplay may include aligning the rendering center of the electronicdisplay with the center of the optical element.

FIG. 8A is a flow chart illustrating an example process 800 of automaticposition determination of HMD optics, in accordance with aspects of thepresent disclosure. Process 800 is one possible process performed by theposition determination controller 702 of FIG. 7.

In a process block 802, the electronic display (e.g., electronic display304 of FIG. 3) generates a pixel pattern of display light. As discussedabove, in some examples, the electronic display may generate the pixelpattern in response to one or more control signals 718 generated by thepattern generator module 712 of FIG. 7. While the pixel pattern isrendered on the electronic display, process block 804 includes the lightsensor (e.g., light sensor 308 of FIG. 3) generating light measurementsin response to the pixel pattern. In some examples, the lightmeasurements include intensity values such as those shown in FIG. 5.Next, in a process block 806, the light sensor module 714 determines alateral position of one or both optical elements of the HMD. The lightsensor module 714 may determine the lateral position based on the lightmeasurements obtained by the light sensor. In some examples, processblock 806 also includes the light sensor module 714 determining an IPDof the HMD based on light measurements received from a light sensor of afirst adjustable eyecup housing (e.g., light sensor 208A of adjustableeyecup housing 202A of FIG. 2) and based on light measurements receivedfrom a light sensor of a second adjustable eyecup housing (e.g., lightsensor 208B of adjustable eyecup housing 202B of FIG. 2).

FIG. 8B is a flow chart illustrating an example process 808 ofdetermining a lateral position of an optical element, in accordance withaspects of the present disclosure. Process 808 is one possibleimplementation of process block 806 of FIG. 8A.

In a process block 810, the light sensor module 714 may determine afirst display coordinate of the electronic display that is aligned withthe light sensor. For example, referring back to FIG. 4, the lightsensor module 714 may determine that the first display coordinateassociated with the column of pixel Pi is aligned with the currentlateral position 404 of the light sensor.

Next, in process block 812, the light sensor module 714 may determine asecond display coordinate of the electronic display that is aligned withthe center of the optical element. As discussed above, with reference toFIG. 4, the determination of the second display coordinate may be basedon the determined current lateral position 404 of the light sensor andon a known or calibrated distance between the light sensor and thecenter of the optical element. In the example of FIG. 4, the currentlateral position 406 of the center of the optical element is determinedto be aligned with the column associated with pixel Pj.

FIG. 9 is a flow chart illustrating an example process 900 of automaticimage alignment with HMD optics, in accordance with aspects of thepresent disclosure. Process 900 is one possible process performed by theposition determination controller 702 of FIG. 7.

In a process block 902, the electronic display (e.g., electronic display304 of FIG. 3) generates a pixel pattern of display light. As discussedabove, in some examples, the electronic display may generate the pixelpattern in response to one or more control signals 718 generated by thepattern generator module 712 of FIG. 7. While the pixel pattern isrendered on the electronic display, process block 904 includes the lightsensor (e.g., light sensor 308 of FIG. 3) generating light measurementsin response to the pixel pattern. In some examples, the lightmeasurements include intensity values such as those shown in FIG. 5.Process block 904 may also include the light sensor module 714determining the lateral position of one or both optical elements of theHMD and/or determining the IPD of the HMD based on the lightmeasurements.

Next, in process block 906, the display adjustment module 716 generatesan offset 722 to adjust a rendering center of the electronic display. Insome examples, adjusting the rendering center of the electronic displayincludes adjusting the location of where images are presented on theelectronic display with respect to the one or more optical elements.Even still, adjusting the rendering center of the electronic display mayinclude aligning the rendering center with the lateral position of thecenter of the optical element.

By way of example, FIGS. 10A and 10B illustrate the rendering of exampleimages 1006 by an electronic display 1002 of an HMD that includes theadjustment of a rendering center, in accordance with aspects of thepresent disclosure. In some implementations, the electronic display ofan HMD may include a rendering center. The rendering center may be adisplay coordinate which serves as a reference for displaying images onthe electronic display. In one aspect, the HMD is configured to centerthe images about the rendering center for presentation to the user.However, as mentioned above, the HMD may include movable optics whichallow users to adjust for various interpupillary distances (IPDs).Changing the position of the optics may change their position relativeto the rendering center of the electronic display of the HMD, which maydegrade the user's viewing experience as some images, such as 3D images,may not appear as intended. By way of example, FIG. 10A illustrates animage 1006 rendered on an electronic display 1002. FIG. 10A also shows arendering center 1008A of the electronic display 1002 as well as acenter (e.g., exit pupil) 1010 of the optical element 1004. As shown inFIG. 10A, the center 1010 of the optical element 1004 is not alignedwith the rendering center 1008A of the electronic display 1002. Thismisalignment between the center 1010 and the rendering center 1008Acould be due to the user adjusting the IPD and/or could be due to theHMD becoming out of calibration. Thus, the image 1006 may not be viewedcorrectly by the user. That is, one or more of the objects included inthe image 1006 may appear distorted, skewed, and/or positionedincorrectly in virtual space.

Accordingly, the automatic image alignment process 900 of FIG. 9 may beperformed to determine a current position of the optics included in theHMD and to adjust the rendering center of the electronic display 1002.For example, FIG. 10B illustrates image 1006 rendered on electronicdisplay 1002 with an adjusted rendering center 1008B. As shown in FIG.10B, the adjusted rendering center 1008B has moved to the left (relativeto rendering center 1008A of FIG. 10A) to align the adjusted renderingcenter 1008B with the center 1010 of the optical element 1004. Asfurther shown in FIG. 10B, adjusting the rendering center may result ina shift of the entire image 1006.

The functionality of one or more components described above withreference to FIGS. 1-10A may be implemented in various ways consistentwith the teachings herein. In some designs, the functionality of thesecomponents may be implemented as one or more discrete components. Inaddition, the components and functions represented by FIGS. 1-10A, aswell as other components and functions described herein, may beimplemented using any suitable means. Such means also may beimplemented, at least in part, using corresponding structure as taughtherein. For example, a means for generating a pixel pattern of displaylight on an electronic display may correspond at least in some aspectsto, for example, the electronic display 304 of FIG. 3, the electronicdisplay 402 of FIG. 4, the one or more processors 706 of FIG. 7, and/orthe pattern generator module 712 of FIG. 7. In addition, a means forgenerating light measurements in response to the pixel pattern maycorrespond at least in some aspects to, for example, the light sensors208A and 208B of FIG. 1, and/or the light sensor 308 of FIG. 3. Evenstill, a means for determining an IPD of the HMD based on one or moreintensity values of the light measurements may correspond at least insome aspect to, for example, the one or more processors 706 of FIG. 7,and/or the light sensor module 714 of FIG. 7. Thus, in some aspects oneor more of such means may be implemented using one or more components,mediums, or other suitable structure as taught herein.

Embodiments of the invention may include or be implemented inconjunction with an artificial reality system. Artificial reality is aform of reality that has been adjusted in some manner beforepresentation to a user, which may include, e.g., a virtual reality (VR),an augmented reality (AR), a mixed reality (MR), a hybrid reality, orsome combination and/or derivatives thereof. Artificial reality contentmay include completely generated content or generated content combinedwith captured (e.g., real-world) content. The artificial reality contentmay include video, audio, haptic feedback, or some combination thereof,and any of which may be presented in a single channel or in multiplechannels (such as stereo video that produces a three-dimensional effectto the viewer). Additionally, in some embodiments, artificial realitymay also be associated with applications, products, accessories,services, or some combination thereof, that are used to, e.g., createcontent in an artificial reality and/or are otherwise used in (e.g.,perform activities in) an artificial reality. The artificial realitysystem that provides the artificial reality content may be implementedon various platforms, including a head-mounted display (HMD) connectedto a host computer system, a standalone HMD, a mobile device orcomputing system, or any other hardware platform capable of providingartificial reality content to one or more viewers.

The above description of illustrated embodiments of the invention,including what is described in the Abstract, is not intended to beexhaustive or to limit the invention to the precise forms disclosed.While specific embodiments of, and examples for, the invention aredescribed herein for illustrative purposes, various modifications arepossible within the scope of the invention, as those skilled in therelevant art will recognize.

These modifications can be made to the invention in light of the abovedetailed description. The terms used in the following claims should notbe construed to limit the invention to the specific embodimentsdisclosed in the specification. Rather, the scope of the invention is tobe determined entirely by the following claims, which are to beconstrued in accordance with established doctrines of claiminterpretation.

What is claimed is:
 1. A head mounted display (HMD), comprising: anelectronic display configured to generate a pixel pattern of displaylight; an optical lens element disposed to pass the display light to auser of the HMD; a light sensor disposed proximate to the optical lenselement, wherein the light sensor and the optical lens element aremounted on an adjustable eyecup housing, and the light sensor is toreceive incident light from the electronic display and from the incidentlight generate light measurements in response to the pixel pattern,wherein the pixel pattern is selected to be varied along rows andcolumns of the electronic display in a non-sequential or sequentialmanner to generate light measurements to be analyzed to determine alateral position of the optical lens element with respect to theelectronic display, after adjustment of an interpupillary distance ofthe HMD; and a position determination controller to determine thelateral position by: determining a first display coordinate of theelectronic display that is aligned with the light sensor based oncorresponding intensity values of the light measurements; anddetermining a second display coordinate of the electronic display thatis aligned with a center of the optical lens element based on the firstdisplay coordinate and a calibrated distance between the light sensorand the center of the optical lens element.
 2. The HMD of claim 1,further comprising the adjustable eyecup housing, wherein the adjustableeyecup housing is configured to allow lateral movements of the opticallens element to adjust the lateral position of the optical lens elementwith respect to the electronic display.
 3. The HMD of claim 2, whereinthe adjustable eyecup housing is further configured to allow the lateralmovements of the optical lens element relative to another optical lenselement of another eyecup housing of the HMD for adjusting theinterpupillary distance.
 4. The HMD of claim 1, wherein the lateralposition is a position of an exit pupil of the optical lens element withrespect to at least one pixel of the electronic display.
 5. The HMD ofclaim 1, wherein the position determination controller is furtherconfigured to determine the interpupillary distance of the HMD based onthe lateral position of the optical lens element.
 6. The HMD of claim 1,wherein the light sensor comprises a photodiode, a phototransistor, or aphotoresistor.
 7. The HMD of claim 1, wherein the pixel patterncomprises a single column of pixels, wherein each of the lightmeasurements includes an intensity value measured by the light sensorwhile the single column of pixels is illuminated at a respective displaycoordinate of the electronic display.
 8. The HMD of claim 1, wherein thepixel pattern comprises multiple columns of pixels, wherein each of thelight measurements includes an intensity value measured by the lightsensor while the multiple columns of pixels are simultaneouslyilluminated at a respective display coordinate of the electronicdisplay.
 9. The HMD of claim 1, wherein the pixel pattern comprises atleast one column of pixels segmented into several groups of pixels,wherein each of the light measurements includes an intensity valuemeasured by the light sensor while the at least one column of pixels isilluminated at a respective display coordinate of the electronicdisplay.
 10. The HMD of claim 1, wherein the pixel pattern comprises asingle pixel, wherein each of the light measurements includes anintensity value measured by the light sensor while the single pixel isilluminated at a respective display coordinate of the electronicdisplay.
 11. A head mounted display (HMD), comprising: one or moreelectronic displays configured to generate a pixel pattern of displaylight, wherein the pixel pattern is selected to be varied along rows andcolumns of the one or more electronic displays in a non-sequential orsequential pattern to generate a first plurality of light measurementsand a second plurality of light measurements to be analyzed to determinelateral positions of a first optical lens element and a second opticallens element with respect to the electronic display; a first adjustableeyecup housing that includes: the first optical lens element disposed topass the display light to a user of the HMD; a first light sensordisposed proximate to the first optical lens element to receive incidentlight from the one or more electronic displays and from the incidentlight to generate the first plurality of light measurements in responseto the pixel pattern; a second adjustable eyecup housing that includes:the second optical lens element disposed to pass the display light tothe user of the HMD; a second light sensor disposed proximate to thesecond optical lens element to receive incident light from the one ormore electronic displays and from the incident light generate the secondplurality of light measurements in response to the pixel pattern,wherein the first and the second adjustable eyecup housings are furtherconfigured to allow the lateral movements of the first and secondoptical lens elements relative to one another for adjusting aninterpupillary distance; and a position determination controllerconfigured to: determine first and second display coordinates of theelectronic display that are aligned with the respective first and secondlight sensors based on corresponding intensity values of the first andsecond plurality of light measurements; and determine third and fourthdisplay coordinates of the electronic display aligned with centers ofthe first and second optical lens elements based at least in part on thefirst and second display coordinates and calibrated distances betweenthe first and second light sensors and respective centers of the firstand second optical lens elements to determine the interpupillarydistance.
 12. The HMD of claim 11, wherein the center of the firstoptical lens element comprises a first exit pupil of the first opticallens element, and wherein the center of the second optical lens elementcomprises a second exit pupil of the second optical lens element. 13.The HMD of claim 11, wherein the pixel pattern comprises a single columnof pixels, wherein each light measurement of the first plurality oflight measurements includes an intensity value measured by the firstlight sensor while the single column of pixels is illuminated at arespective display coordinate of the one or more electronic displays.14. The HMD of claim 11, wherein the pixel pattern comprises multiplecolumns of pixels, wherein each light measurement of the first pluralityof light measurements includes an intensity value measured by the firstlight sensor while the multiple columns of pixels are simultaneouslyilluminated at a respective display coordinate of the one or moreelectronic displays.
 15. The HMD of claim 11, wherein the pixel patterncomprises at least one column of pixels segmented into several groups ofpixels, wherein each light measurement of the first plurality of lightmeasurements includes an intensity value measured by the first lightsensor while the at least one column of pixels is illuminated at arespective display coordinate of the one or more electronic displays.16. A head mounted display (HMD), comprising: means for generating apixel pattern of display light on an electronic display; a right-eyeoptical lens element disposed to pass the display light to a user of theHMD; a left-eye optical lens element disposed to pass the display lightto the user of the HMD, wherein the right-eye optical lens element andthe left-eye optical lens element are moveable for adjusting aninterpupillary distance of the HMD; means for receiving incident lightfrom the electronic display and from the incident light generating lightmeasurements in response to the pixel pattern, wherein the pixel patternis selected to be varied along rows and columns of the electronicdisplay in a non-sequential or sequential manner to generate the lightmeasurements to be analyzed to determine lateral positions of theright-eye optical lens element and the left-eye optical lens element;and means for calculating the lateral positions by: based oncorresponding intensity values of the light measurements, determining afirst display coordinate of the electronic display for a selectedright-eye optical lens element or left-eye optical lens element that isaligned with the means for receiving the incident light; and determininga second display coordinate of the electronic display that is alignedwith a center of the selected right-eye optical lens or left-eye opticallens element based on the first display coordinate and a calibrateddistance between the light sensor and corresponding center of theselected right-eye optical lens element or left-eye optical lenselement.
 17. The HMD of claim 16, further comprising a right-eyeadjustable eyecup housing and a left-eye adjustable eyecup housingconfigured to allow lateral movements of the right-eye optical lenselement and left-eye optical lens element to adjust the lateral positionof the optical lens elements with respect to the electronic display.